Question: I live in northern Minnesota, and I’m thinking of buying a home greenhouse. Any helpful hints?
Answer: You’ll be pleased by the wide range of ready-made greenhouses and kits on the market, but the number of options can be overwhelming. To narrow down your choices, start by researching zoning requirements in your area. A greenhouse that’s attached to your home will probably have more restrictions than a small, free-standing structure.
Next, think about how you plan to use your greenhouse. Are you hoping to merely extend the growing season by a few weeks in spring and fall, or do you want to keep plants alive inside the structure all winter long? If the former, almost any greenhouse will do. If the latter, good insulation and even supplemental heating are critical.
Greenhouse siting is also important. You’ll need a location on your property that receives at least six uninterrupted hours of sunshine every day. If the structure will be attached to your house, it should be on the south side for optimal sunlight. Also, ask yourself these questions: Is there a water source nearby so you won’t have to haul it to your plants? Will you want electricity for ventilation, heating, and lighting?
Solar-powered vent operators are available. You can buffer temperature extremes with thermal mass, such as a brick or stone north wall, or water-filled barrels painted black that will slowly radiate the sun’s stored heat back into the greenhouse at night — but these require advance planning and, in the case of the barrels, extra space.
Another important decision is glazing. This will have to be a balance between light transmission and insulating factors. Polycarbonate is common because it’s lightweight, durable, and available in different thicknesses and layers. The more layers you use, the better your greenhouse will retain warmth — but thick layers will filter out more light, and that could be a concern in northern Minnesota’s cloudy winters if you’re planning on growing in January and February. Glass lets in a lot of light and is cheaper, but it’s also heavy and easily breakable, and single layers have a poor insulating factor. Many greenhouse owners swear by double-layered, honeycombed polyethylene, marketed as “Solexx.” It’s cheaper than polycarbonate, but doesn’t transmit as much light.
--Rebecca Martin, group editor for Ogden Publications, as well as an avid organic gardener
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